Our laboratory recently identified a novel, 39 kDalton initiator (lnr) binding protein of Trichomonas vaginalis which we named IBP39.Because Inr is present in all T. vaginalis genes as the only core promoter element, we believe that IBP39 may be essential in T. vaginalis gene transcription. We propose to further characterize IBP39 by first identifying the domain(s) that are responsible for recognizing the Inr. We plan to achieve this by studying binding interactions between deletion mutants of IBP39 and both wild type and a mutant lnr, as validated in our laboratory. Furthermore, we would like to identify amino acids that are essential in the interaction with the Inr sequence. We propose to perform in situ site-directed mutagenesis experiments targeting residues based on results we obtain from the deletion mutant studies. Transcription factors are known to work together in the initiation of transcription. We hypothesize that IBP39 may be a member of a larger protein complex that binds to the Inr. Therefore, iBP39 will be used in a series of experiments, such as size exclusion and affinity chromatography, native gel electrophoresis and the yeast-two-hybrid system to identify other proteins that interact with IBP39. Last but not least, we would also like to explore the idea that IBP39 may be essential in T. vaginalis gene transcription by testing the effect of knocking out IBP39. If IBP is found to be essential, it might be an excellent drug target against Trichomoniasis.